DESCRIPTION: (Applicant's Abstract) Researchers rely on substance abusers' self-reports to evaluate outcomes in counseling programs, innovative treatment services, pharmacologic interventions, and other topics. However, substance abusers, especially cocaine abusers, often substantially understate their drug use. In two studies at the proposed site, underreporting was more common among cocaine abusers who had received little or no treatment than it was among treatment completers. Thus, those with little or no treatment may report nearly as much improvement as completers, leading to a considerable underestimation of treatment effectiveness. The current project uses the Addiction Severity Index (ASI) to study whether admission of substance use increases after a warning that urine and hair analyses will be obtained, and after some changes in the ASI. Preliminary results suggest that rather than reveal cocaine use, many respondents adopt new strategies to conceal it. However, data gathered via telephone or in-person interviews were quite comparable. Soon, Computer Assisted Self-Interview (CASI) systems may be widely used at both intake and follow-up in the substance abuse field. They may elicit more valid reports of substance use. The proposed 2-year Continuation will compare the first full ASI telephone Audio-CASI system to standard live telephone interviews at post-treatment follow-up (N=418). We also propose to compare two very different in-person ASI CASIs at intake (N=540) to each other and to standard in-person administration. To the best of our knowledge, this will be the first large-scale tests of these new systems. At both intake and follow-up, we propose to directly assess the validity of self-reports of substance use by means of urine and hair analysis. We will also explore how incentives for concealing drug use affect self-report validities. An expansion to a second site (the Belmont Center) will provide a larger number of subjects with a wider range of ethnicity and substances of abuse. The results may benefit treatment programs, clinicians and researchers involved in assessing treatment outcomes.